You already know what not to eat to protect yourself from stroke, so you stay away from foods that are high in salt and artery-clogging fats. And you probably know that you should be eating lots of fruits, vegetables and whole grains for their fiber and healthful antioxidants. But there’s another nutrient that you need for stroke protection. Protein—yes, protein. And here’s the surprise—although nuts, beans and grains are all protein sources known for helping heart health, the results of a new study suggest that a certain kind of animal protein may be the best for stroke protection.
You’re probably thinking that makes no sense. Many studies have shown that protein-rich diets, particularly diets in which the protein mostly comes from animals, are not beneficial for stroke prevention. At the same time, other studies have shown that protein-rich diets can reduce stroke risk.
Researchers from China who tried to make sense of conflicting studies about protein and stroke risk found that people whose diets included a moderate to moderately high amount of protein—particularly animal protein (up to 2.19 ounces per day compared with the average US recommended amount of 1.6 to 2 ounces of protein from any source)—were less likely to have a stroke than people who included only a little bit of protein in their diets. In looking at a group of studies that, in total, included 254,489 people, the researchers discovered that people who ate the most protein from any source had a 20% lower risk of stroke compared with those who consumed the least protein. Also, interestingly, the more protein eaten from any source, the lower the risk of stroke. That is, for every 0.7 ounces more of protein (moderately) consumed, stroke risk dropped by 26%.
In studies that specifically looked at either animal protein or vegetable protein, the researchers discovered that eating more, rather than less, animal protein reduced risk by 29% and eating more, rather than less, vegetable protein reduced by risk 12%. The range between high and low consumption in the studies on vegetable protein wasn’t that wide, though, which may be why a larger difference in stroke risk reduction wasn’t seen in them.
THE BEST SOURCE OF PROTEIN
Here’s the most valuable takeaway from the meta-study, in my opinion—the greatest benefit for stroke protection, by far, seemed to come from getting animal protein from fish.
When the Chinese researchers looked more closely at the individual scientific studies, they noticed something striking about cultural and regional differences that put the puzzle about protein and stroke risk all together for them. Studies from Japan—a country in which fish consumption is particularly high—showed that people who ate the most protein had half the stroke risk of people who ate the least. And a research paper from Sweden—another country big on fish-eating—showed that stroke risk was reduced by 26% in higher consumers of protein. Compare these risk numbers to the one pooled from four studies from the United States, whose residents, on average, get the least amount of their protein from fish. Stroke risk reduction from higher protein consumption was only 9%.
How does protein reduce stroke risk? One theory is that it does so by lowering blood pressure, a well-known risk factor for stroke. Red meat, poultry, fish and dairy all contain L-arginine, an amino acid that our bodies convert to nitric oxide. Nitric oxide causes blood vessels to open wider, which improves blood flow and reduces blood pressure. But this good effect might be countered by the types of fat (and cholesterol) in red meat and dairy. This is why fish, which contains other heart-healthy nutrients such as omega-3 fatty acids, looks like the better choice.
In looking over this study, which doesn’t prove but makes a strong case that fish should be our main source of protein, I am reminded of what we’ve been told about the value of the Mediterranean diet—a diet high in whole grains, vegetables, olive oil, fish and fruit and low in red meat. We know it is beneficial for stroke reduction. So, if you’re already fortifying your diet with vegetables and protein and especially substituting fish for red meat, you’re doing it right. If not, consider making this heart-healthy change now.